1. Field of the Invention
The present invention relates to a power source system for a vehicle and, more specifically, to one which includes two systems with different voltages to be controlled.
2. Description of Relevant Art
Recently, an automotive is developed in progress, which is equipped with a motor generator in advantageous fuel costs. The automotive is operated with power sources of two systems which include a high voltage system (for example, 42 volt) and a lower voltage system (for example, 14 volt). This kind of automotive is equipped with a power source, which detects a speed of a vehicle to control the motor generator on the basis of the detection for improvement of fuel costs and for protection of a battery.
As an automotive operated with power sources of two systems, a serial-hybrid automotive is cited. The automotive employs a technology which adjusts an electric power generation in amount on the basis of a state of a vehicle.
For example, the Japanese Patent Application Laid-Open Publication of NO. 10-178703 discloses an xe2x80x9celectric power generation controller for a hybrid type electric automotivexe2x80x9d. The controller, as shown in FIG. 4, includes a generator 52 to be driven by an engine 50. The controller includes a battery 58 for receiving a power from generator 52 to supply a power to motor 56. Based on the load of battery 58 and speed of a vehicle, generator 52 is determined on the upper limit (upper threshold) of electric power to be generated. Generator 52 is controlled to generate electric power within the upper limit.
The Japanese Patent Application Laid-Open Publication of NO. 10-164710 discloses an xe2x80x9celectric power source controller for a hybrid type electric automotivexe2x80x9d. The controller is equipped with a battery and an engine electric power generator as a power source. When the battery is lowered in the residual capacity (charging rate), the generator produces an electric power.
These automotive include loads of a high voltage system as well as a conventional low voltage system. This needs converter to convert a high voltage into a low voltage. This voltage converter and the low voltage loads connected to each other are loads for the high voltage system in view of the motor generator and the higher voltage battery.
Loads in the low voltage system include a kind of lamp, with the electric power consumption which occupies a considerable ratio relative to a whole electric power consumption of an automotive. Thus, when conversion of power in the voltage converter has no relationship with control on the motor generator, improvement of fuel costs due to the control on the motor generator is reduced.
The invention is directed to a power source system for a vehicle, which allows control of a electric power generation in accordance with a vehicle under various conditions to improve fuel costs and to further effectively protect battery.
A first aspect of the invention provides a power source system for a vehicle. The system includes a generator for producing a power. The system includes a first battery for being charged by the generator to supply a power of a first voltage to a first load. The system includes a second battery for supplying a power of a second voltage to a second load. The system includes a converter for receiving a power of the first voltage from the first battery to convert the power of the first voltage into a power of the second voltage to supplied to the second battery. The system includes a controller for controlling output of the converter, in accordance with one of states of the generator, a charge of the first battery, the first load, a charge of the second battery, and the second load.
Preferably, the controller includes a decision maker for deciding the generator to be operated in one of a power mode and a regenerative mode. The power mode is for consuming a power. The regenerative mode is for regenerating a power. The controller controls the converter, based on decision of the decision maker.
Preferably, the controller controls the converter to output a predetermined current desired voltage value if the decision maker decides the generator in the power mode when the first battery is charged greater than a predetermined lower threshold.
Preferably, the controller controls the converter to lower a current desired voltage if the decision maker decides the generator in the power mode when the first battery is charged lower than the lower threshold.
Preferably, the controller controls the converter to keep a current desired voltage if the decision maker decides the generator in the power mode when the first battery is charged lower than the lower threshold.
Preferably, the controller controls the converter to keep a current desired voltage if the decision maker decides the generator in the regenerative mode when the first battery is charged lower than the lower threshold.
Preferably, the controller controls the converter to raise a current desired voltage if the decision circuit decides the generator in the regenerative mode when the first battery is charged greater than the lower threshold and the current desired voltage is lower than a maximum desired voltage.
Preferably, the controller controls the converter to keep a current desired voltage if the decision maker decides the generator in the regenerative mode when the first battery is charged greater than the lower threshold and the current desired voltage is greater than a maximum desired voltage.
A second aspect of the invention provides a power source system for a vehicle. The system includes a generator for producing a power. The system includes a first controller for controlling the generator. The system includes a first battery for being charged by the generator to supply a power of a first voltage to the first load. The system includes a second battery for supplying a power of a second voltage to a second load. The system includes a converter for receiving a power of the first voltage from the first battery to convert the power of the first voltage into a power of the second voltage to be supplied to the second battery. The system includes a second controller for controlling output of converter, in accordance with one of states of the generator, a charge of the first battery, the first load, a charge of the second battery, and the second load. The first controller is housed in a first connection box. The converter and the second controller are housed in a second connection box.